Coasts and Marine

The Port Phillip and Western Port region has more 600 kilometres of coast fronting Port Phillip Bay, Western Port and Bass Strait. Coastal environments are the interface between marine and terrestrial ecosystems and are vital to their productivity, health and resilience. They are highly valued economically, host significant geological and cultural sites and are visited by millions of people annually.

Coastal environments include:

  • Bay and ocean beaches
  • Sand, rock, mangrove and cliff
  • Public land, private land and different land uses
  • Places of significant environmental value such as Ramsar sites
  • Places of significant social value such as recreational beaches.

Indigenous relationships with coastal and marine environments stretch back many thousands of years and are reflected in the cultural sites present along Victoria’s coast and in this region. These sites, which include shell middens and camping places, date back as far as 6,000 years which is when the sea rose to its present level.

A healthy marine and coastal environment is biodiverse and dynamic. It contains functioning biological, physical and chemical interactions that support the local environment’s many and varied plants and animals. It is able to operate as a dynamic, constantly changing system.

The proximity of coastal areas to metropolitan Melbourne ensures they are popular, but also puts them under a lot of pressure. Key threats to these environments include population growth and urbanisation, commercial and recreational fishing, and climate change, which can lead to habitat destruction and fragmentation, pest plants animals, rising sea levels, and changes to water flows and salinity.

The Port Phillip and Westernport CMA works in partnership with agencies to protect and rehabilitate coastal areas under threat from erosion, vegetation loss, oil spills, inundation, inappropriate development and discharge of stormwater and sewerage effluent. Coastcare also operate in this region, working with community groups who are implementing coastal management and protection projects.

Key facts

  • The region’s ome to more than 12,000 plant and animal species, many not found anywhere else in the world
  • Contain examples of all eight of Victoria’s different wetland types
  • Provide important habitat for 14 nationally and internationally recognised shorebird species
  • Half of the 50 vegetation types along the region’s coasts are endangered
  • Some coastal areas could be submerged by 2100 if sea level rise

Port Phillip Bay

Port Phillip is the entrance to Australia’s busiest port, it covers 1,950 square kilometres and is one of Victoria’s most popular recreational destinations.

Over 3 million people live around its shore, making Port Phillip Bay Australia’s most densely populated catchment. The bay is a large expanse of water that is surprisingly shallow in many places. It is one of the largest examples in the world of a shallow embayment in which the sea floor ecosystem is crucial to the overall health of the bay.

It covers 1,930 square kilometres and is 24 metres deep at its deepest central point 50. Its narrow entrance, ‘the Rip’, is three kilometres wide and reaches depths up to 94 metres. The narrow entrance, to the bay creates significant tidal currents within the lower part that help to sustain environmental values such as sponge communities.

The Bay is surrounded by a populated region with urban and agricultural activity, making it particularly susceptible to catchment based inputs. The rivers that run into Port Phillip Bay include the Yarra River, with other inputs from the Maribyrnong, Werribee, Patterson and Little rivers, from Kananook, Mordialloc and Kororoit creeks and from a multitude of stormwater drains.

Western Port

Western Port is a large tidal bay in southern Victoria, Australia opening into Bass Strait. It is the second largest bay in Victoria. Geographically, the bay is dominated by the two large islands, French Island and Phillip Island.

It is 680 square kilometres in area and is highly valued for its environmental benefits, highlighted by the establishment of three marine protected areas. It contains numerous sea-grass, mudflat, mangrove, saltmarsh and deepwater communities with high habitat values.

While Western Port is generally shallow with 40 per cent of its northern area exposed as mud flats at low tide, the south western part is known for its deeper channels of around 14.3 metres in depth. It is home to many bird and animal species and is listed under the Ramsar Convention for its habitat for migratory water birds.

Western Port has a highly diverse variety of habitat types. In its northern part, are unique and highly productive communities of seagrass, mangrove and saltmarsh habitat. This habitat provides food and shelter for invertebrates, insects, crabs, reptiles, fish and birds, and critical nursery habitats for a range of commercial and recreational fish species.

The area around the bay and the two main islands were originally part of the Boonwurrung nation’s territory prior to European settlement. The bay was first seen by Europeans in 1798 when an exploration crew journeyed south from Sydney to explore Australia’s south eastern coastline.

Threats to Western Port include algal blooms from increased nutrient loading, sedimentation, changes in fresh water quality, clearing of native habitat, impacts from agriculture, introduction of exotic marine organisms and impacts from climate change.

Protecting the region’s coastal areas

The environmental significance of the region’s coastal and marine areas has been recognised in a number of ways:

Marine protected areas

  1. Port Phillip Heads Marine National Park
  2. Yaringa Marine National Park
  3. French Island Marine National Park
  4. Churchill Island Marine National Park
  5. Point Cook Marine Sanctuary
  6. Jawbone Marine Sanctuary
  7. Ricketts Point Marine Sanctuary
  8. Mushroom Reef Marine Sanctuary

Related information